This invention relates to disk drive systems. More particularly, the invention relates to the protection of disk drive linear actuators from mechanical shock forces.
Disk based data storage devices for storing digital electronic information have been in use in the computer industry for several decades. The storage devices operate by storing digital information on disk media such as magnetic, magneto-optical or optical medias. The disks can be either rigid or flexible and are mounted on a rotating hub. These storage devices are commonly referred to as disk drives. Disk drives store data on removable media cartridges or they are fixed media drives.
Removable media drives accept the disk media in the form of a removable cartridge. When the cartridge is inserted into a disk drive, a spindle motor in the drive couples with the disk hub in order to rotate the disk within the cartridge at a given speed. The outer shell of the cartridge typically has a media access opening proximate one edge. The access opening provides the recording heads of the drive with access to the disk. To cover the head access opening when the cartridge is not in use, a shutter or door mechanism is provided that prevents dust or other contaminants from entering the cartridge and settling on the recording surface of the disk. The shutter is commonly biased to a closed position with a spring bias. To open the shutter and gain access to the media, the drive employs a mechanism that overcomes the spring bias.
Disk drives typically employ either a linear actuator mechanism or a rotary actuator mechanism. The actuator positions the read/write head(s) of the disk drive on the recording surface(s) of the disk. The linear or rotary actuators must be able to move off, and away from, the storage medium to a retracted position, also commonly referred to as the park position. This retracted position prevents damage to the head(s), for example, when a cartridge is inserted and removed from the disk drive or when the drive is moved. Moreover, many removable cartridge disk drives employ a pair of opposing read/write heads for recording and reproducing information on both side of a storage medium. Typically, the opposing heads are disposed on flexible suspension arms at the distal end of an actuator that allow the heads to fly closely over the respective surface of the rotating disk.
Increasingly, disk drives must meet rigorous mechanical shock and vibration standards. Rigorous standards are necessary because current drive applications include hand held computers, digital cameras, and other portable computer appliances. The portable nature of these applications increase the likelihood that the drive will be subject to shocks and vibrations. For example, the computer appliance may be dropped or jarred. When experiencing mechanical shock or vibration, the actuator could inadvertently move from its retracted position causing serious damage to delicate drive components.
The protection of actuators from mechanical shocks and vibration has been addressed by prior art mechanisms. For example, U.S. Pat. No. 5,404,257 (Alt) has used an inertial latch mechanism that allegedly prevents a disk drive actuator from moving out of a retracted position during mechanical shocks. The Alt inertial latch mechanism accomplishes this by employing an inertial body and pivotal latch member. When a mechanical shock is experienced by the drive, the shock force causes the inertial body to contact the latch. As a result, the latch member closes on an abutment on the actuator and prevents it from moving completely out of the parked position. The latching is accomplished without the aid of electrical power.
U.S. Pat. No. 6,091,587 Hatch et al. also describes a mechanism for restraining the head components in a disk drive. The mechanism comprises a mass member having a pivot point. The pivot point is located substantially proximate to the center of mass so that the mass pivots in response to an external force. The mechanism also comprises spring member that biases the mass to a predefined position. Additionally, two latch members are coupled to the mass member, each latch member having a protruding cammed end that is adapted to engage the component. The latch members are arranged such that their respective cammed ends protrude in opposing directions. The latch members are coupled to the mass member so that the center of weight of the inertial mass is substantially opposite to the latch members on the other side of the pivot point.
U.S. Pat. No. 5,650,891, Thayne et al., describes a ZIP(copyright) drive having a linear actuator for use in Notebook computers.
It is an object of the present invention to provide an improved inertial latch for linear head actuator drives.
In accordance with the present invention, an inertial latch for a linear actuator disk drive includes a latch on the carriage assembly and an arm rotating about a pivot. One end of the arm engages the latch. A counterweight on the other end of the arm has a key which slides linearly in a slot as the carriage assembly moves linearly. The key fits into a keying portion of a slot in the chassis. The key cannot move out of the keying portion of the slot if the counterweight is titled by gravity, shock or the like.
In accordance with the invention no external electro-mechanical devices are used to actuate the head protect mechanism. The head actuator itself actuates the latch. Inertial forces acting on the actuator latch the actuator during either linear or rotational or combined shock conditions.
Further in accordance with the invention, a ramp feature on the actuator resets the latch during parking of the heads. An inertial force on the actuator (the total moving mass) will also act on the balanced mass at the end of the rotary arm. This action will prevent the heads moving to an unprotected position.
Pendulum action of the counterweight latches the rotary arm during rotational shock condition. The key slot on the chassis does not allow the key on the counterweight to slide the counterweight if tilted due to rotary shock. The key has a round shape which slides against the rounded corner of the key slot.
The geometry of the rotary action of the latch and linear action of the actuator is used to release the heads by the action of the head actuator.
Other objects, features, and advantages of the invention will be better understood from the following, more detailed description and appended claims.